In most photographs of German HSF Warships ( Light cruisers and everything bigger ) hanging in the rigging of the main mast (aft mast ) are two cone shapes , usually one point up and the one on the other side of the mast point down .

Shore signal stations hoist (or used to hoist ) cones to warn of Gales , and the expected wind direction ( 2 x point up = North , 2 x point down = South , 2 with points together = West , 2 with bases together = East ) These dont appear to be for that purpose .

One suggestion has been put to me that they are used to signal turns to the next astern , but I am doubtful of that .

Another suggestion was that they are traffic direction indicators for the constant boat traffic while the ship is laying out on a mooring bouy , ie on the Port side go from stern to bow , on the Starboard side go bow to stern ( say ) so as to avoid boat collisions and accidents to personnel .

..... I would need to go hunting through a number of my books (because I can't recall that exact source), but - IIRC - the cones to which you refer were used to signal speed changes within the formation.

Cones were certainly used to indicate speed in the US navy - but from the foremast yardarms (you can see them on most photos of US pre-dreadnoughts under way - there are one or two photos of Japanese ships with them as well, but most don't seem to have them). However, these cones on the mainmast on German ships vanish into the smoke plume at speed so if they were a signalling system they can't have been very effective. (After a quick search I was only able to find two photos where the two cones were definitely at a different height, incidentally - one in port and one at sea - so if it was for signalling it was in circumstances that weren't likely to get photographed). The Russians also used these cones on the mainmast from about 1895 (but not universally, as far as I can tell), which seems to be about the same time the Germans started, but they're gone from post-RJW photos.

Im lacking the I T skills to put a photo of these up here , i'm afraid , BUT , Ive just had a look at the SMS Lutzow topic ( next door ) and on four out of six of the photographs there you can see them , most clearly on the last one .As I say , these seem to appear in most pics of any ship bigger than Light cruisers .

The point about them being obscured by smoke is a good one , one of the photos shows that quite clearly , and on Lutzow they appear to have been put exactly at funnel top height , about the worst spot if you were using them to signal something .

Change of speed signal --- that sounds plausible , maybe this is the "stowed" position . Hmmmmmmm ........

Ive just had another look , and you can see them much better on the SMS Moltke topic , especially the one where she is laying out on a bouy ( in Kiel ? )

" Relax ! No-one else is going to be fool enough to be sailing about in this fog ."

Here´s a photo captured aboard Gneisenau while in transit through the Nord-Ostsee Kanal in August 1939. Take a closer look into her mainmast - over the funnel outlet at level with the converging point of her tripod legs. Are these triangular signals the same ones as you noticed in the aft mast (main) aboard the SMS ships...? If so then yes, its the rudder position indicators.

Note that these signals had an onboard use rather than as signal between ships. They would serve as a quick reading of rudder position to any man aboard- within sight of the mast of course. Both triangles would usually be seen either at level with each other; rudder midship, or in a diagonal sort of appearance (high and low) during turns. For the record, I`m compelled to believe down is synonymous with inwards rudder position - if port side triangle is lowered then port rudder is performing a starboard turn.

And just to have mentioned it before someone decides to ask, the `box with the cross´ lowered from the yardarm at port side of the foretop artillery platform probably serves as outboard signal that the "ship`s maneuverability is impaired"

But ........ Rudder position indicators ..... why would anyone want to glance up and see ? Who , and in connection with what tasks ?Fore and aft deck crews during mooring ? ..... but why ?On the conning and control positions you would use a "telegraph" type of indicator , like you use to send engine orders ... also , are these cones worked by the rudder mechanisms ? ie a physical cable connection that goes up/down or in/out like a steering cable around a drum as the helm shifts over ? .... pretty archaic set-up , if it is . .... And liable to being shot away in action . And concealed by smoke , at least in the WW1 ships .

I can see the point of telling TUGS , or Dockyard staff , where your rudder is . I cant see the reason for that information to be universally available in-board though .

And the "cross-in-a-frame thing" , there are perfectly good International code signals "I am manoeuvering with difficulty" "I am not under command" "keep clear of me" etc , etc , or is that something peculiar to the K W Kanal transits ?

Puzzled ............... !

" Relax ! No-one else is going to be fool enough to be sailing about in this fog ."

The connection from wheel to rudder doesn´t go thru those cables, but straight from the bridge down to the lower decks, and then aft to the commanding engines. I presume that the function of the rudder indcator is to notice the ship next astern of an impending veering, as ships don´t respond instantly to rudder movement. So the wheelman of the ship astern, on seeing the rudder angle change in the preceding ship, will do the same without waiting to see the ship veering, as waiting would produce a lag down the line and disturb the manouvre.

When I said the indicators served as a quick reading of rudder position to any man aboard this was under the presumption that the person to consult these would be one in need of confirmation, this being say an Admiral at the wing of the Admiral´s bridge currently unable to consult a helm indicator whereupon a quick glance towards the mast will inform him whether a recently issued order of course alteration is being effectuated. Or for that matter a ship commander at a lower level, currently unable to consult the bridge instruments.

It is possible, as Marcelo pointed out, these served as signals to the ship in her wake that a course alteration was in the making - though also to be addressed, exhaust smoke would then have an unfortunate effect upon the effect of these.

I can see the need to signal/indicate to the next astern , as his bows are only 2 to 3 shiplengths behind your stern . At 20 knots or so that doesn't give you time to see the one in front actually begin to swing , before you give your own helm order , especially in a ponderous battleship . If you go late , but make the same turn , you'd stand a good chance of crunching into the chap in front .

With regard to how they work , I presume one indicates the rudder(s) are turned to turn the ship to port , and the other to starboard , and the reason one is point up and the other is point down is so wherever you saw it from and no matter how fleeting the view , you would be unlikely to mistake port for starboard . OK . So did they have two guys pulling on the halliards for these , or are they connected physically to the steering mechanism ?

" Relax ! No-one else is going to be fool enough to be sailing about in this fog ."

Hammy, now that Terje described their function, I remember that Hood had something alike, no cones but flags. I believe that they are interconnected to the wheel mechanism, later in the day I will look in the AOTS volume to confirm.

Thanks Marcelo .Ive been having a look at some pictures of British pre-dreadnoughts and cruisers , and several of those show shapes hanging in similar positions , so it looks like this was a pretty universal thing at the time .

" Relax ! No-one else is going to be fool enough to be sailing about in this fog ."